Method and apparatus for sand reclamation



A. DEN BR Aug. 21, 1945.

EEJEN ETAL 2,383,045

METHOD AND APPARATUS FOR SAND RECLAMATION Filed March 30, 1942 WATEE 6.FIN ES Patented Aug. 2l, 1945 UNITED STATES PATENT OFFICE METHOD ANDAPPARATUS FOR SAND REULAMATION poration of Illinois Application March30, 1942, Serial No. 438,760

8 Claims. (Cl. 22-89) The present invention relates to a method forreclaiming or cleaning sand and to apparatus for carrying out thismethod. More particularly, the present invention is concerned with theprovision of a. method and suitable apparatus for cleaning and otherwisereclaiming used foundry sand, particularly foundry core sand, so as tomake this sand suitable for use in forming new foundry molds.

It is common foundry practice to use what is known as core sand formaking cores for interior and exterior surfaces. This core sand usuallyconsists of a mixture of sand and any one of several green bindingagents which retain the sand in place until the core is baked and abinding agent which gives the core strength and rigidity after bakingand during the pouring operation. The binding agent most frequently usedfor the latter purpose is core oil, although cement or pitch or othermaterials are sometimes employed.

A typical core may be formed by mixing proper proportions of sand. coreoil and a green binder, molding the material to the desired shape andthen baking the core to oxidize the core oil After the baking step, thecore thus made and used has considerable strength and should adequatelyresist damage until it can be used and further should resist thehydrostatic head and the erosive action of the flowing metal poured intothe mold.

Shortly after the metal has started to set, the heat from the moltenmetal accomplishes a burning of the core oil i'llm sufficiently topermit easy disintegration of the cores'. ThusI after the metal hassolidiiled and the mold is broken open, the core sand should flow out ofthe mold in a more or less granulated form. Core sand containing a coreoil residue is black after the pouringv operation and is composedlargely of sand grains, each of which is substantially completely coatedwith a deposit consisting of carbon and partially carbonized core oil.This deposit adheres to the sand grains with great tenacity and rendersthe sand practically useless for further use in the formation of foundrycores, since cores formed fromsuch sand will have little strength.

In the past, the problem of reclaiming core sand for reuse has receivedconsiderable attention, but so far as we know, no attempts to reclaimfoundry core sand have been commercially successful.

Since, under ordinary conditions, core sand can be used but once assuch, it will be appreciated that the cost of new sand, together withthe freight charges on this new sand, are a considerable item in thecost oi' castings. In addition, the used core sand must be removed fromthe foundry and frequently must be hauled a considerable distance to a.dump. In fact, in many of the larger foundries, several freight carloadsof used sand must be hauled from the foundry te a dump each day andseveral carioads of new sand must be brought in to take its place.

When cement, pitch, or other core binding agents are used instead ofcore oil, the problem is substantially the same in that because the usedsand grains are covered with a tenacious substance which renders thesand unfit for further use, it must be discarded and replaced by newsand.

It is one of the objects of the present invention to provide a. novelmethod and suitable apparatus for treating used foundry core sand sothat the sand after treatment is Suitable for use in forming new coreand synthetic molding sand.

A further object of the present invention is to provide a novel methodand apparatus fortreating used foundry sand in such a manner that thetreated sand will normally form mold parts of greater :strength thanmold parts formed from new sand.

Still another object of the present invention is to provide a novelmethod and apparatus for cleaning sand which provides clean send etextremely low cost.

Yet another object of the present invention is to provide a novel methodand apparatus for removing tenacious surfsce deposits from sand grainsin a commercially feasible manner and at low cost.

Yet another obiect of the present invention is to provide a novel methodand apparatus for cleaning sand which eliminates the necessity for iarsefoundry sand"dumps and, in addition, permits foundries to reclaimdiscarded sand already placed in dumps.

Still another object is to provide a novel method and apparatus fortreating sand to fulfill the above objectives continuously rather thanin batches.

Other objects and advantages will become apparent from the followingdescription of a preferred embodiment of our invention taken in con-Junction with the accompanying drawing in which:

Fig. 1 is a diagrammatic representation of suitable apparatus forperforming the present invention: and

Fig. 2 is an end view of a roller which forms a.

portion oi' the apparatus used in performing the present invention.

At the upper portion of Fig. 1 in the drawing will be seen a hopper lliwhich serves as a receptacle in which the used foundry sand is placed.This receptacle is comprised of a bin or tank of adequate capacity tocontain the sand to be treated. If desired, it can be comparativelysmall. in which case itwill necessarily have to be filled continuouslyduring operation of the process, or it can be comparatively large andcan be illled at less frequent intervals. The sides of the hopper at itslower portion are inclined inwardly at i2, so as to provide sloping sidewalls to guide the sand toward an outlet opening near the bottom at thepoint indicated by the numeral I4.

The sand to be treated is placed in the hopper l and is Well coveredwith water if it is not already wet, so that the spaces between the sandgrains are substantially completely taken up by the water. Such amixture flows with diiliculty and therefore the wet sand is fed from thehopper I0 through the opening indicated by the numeral I4 and down achute I5 by means of water jets not shown but located opposite theopenings at I4. Ihese jets are fed through a pipe line I8 and thevelocity of the water through these jets can be controlled by a valve 2Dconnected in this pipe line. Since the use of Water jets for the purposeof causing sand or like material to ow through a passage is Well known,no detailed description of these jets need be given here.

'I'he mixture of sand and water ilows down the chute i6 and upon adehydrating shaker screen 22. The screen 22 normally is considerablylonger than it is wide and is inclined so as to have the end whichreceives the sand and water mixture from the chute IB higher than itsopposite end. This screen is kept in constant vibration during operationof the process so as bo cause the wet or damp sand to move over itssurface toward its lowenend. Since the use of vibrating mechanisms forgenerally similar purposes is well known. no special description of thisvibrating apparatus need be given. We have found, however, that avibrating mechanism which gives a frequency of aproximately 3300 cyclesper minute of comparatively short amplitute is suilcient for thispurpose.

The rapid vibration of the screen, together with its downhill slope,causes the sand grains to move toward the discharge end, while a largeportion of the Water mixed with the sand runs through the screen therebymaterially reducing the moisture content of the sand before it isdischarged from the lower end of the screen. We have found that withsuch an arrangement as Just described, the water content of the sand andwater mixture can be reduced to approximately 16 to 18 per cent byweight. Such a mixture of sand and water will neither ow as a liquid norwill it now as does dry sand, but it can be caused to move over avibratory screen in the manner described.

In general, the mesh of the screen 22 should be suiflciently small toretain the major portion of the sand grains upon its upper surface. Itis not advisable. however, to make it sumciently small to retain al1 ofthe fines that it ls desired t0 include in the nal sand mixture, since ascreen of this degree of fineness does not easily permit the flow ofwater therethrough because of the capillary action of the water.

Since the water which flows through the screen contains a portion of thefines which are desired to be included in the final sand mixture. thiswater is collected from beneath the screen in a large funnel 24 and ispassed downwardly through a chute 26 to a sump 28 from which it ispumped through a pipe 3l) by means of a centrifugal type pump 32 orsuitable apparatus back into the hopper I 0. Thus the usable fines arenot lost from the system. It should be appreciated that only acomparatively small portion of the fines pass through the screen 22 andhave to be returned to the hopper l0. At least per cent of the nesordinarily will stick to the larger sand particles and be carried overthe surface of the screen 22 and will be discharged directly with thelarger particles from the lower end of the screen.

The sand dehydrated to aproximately 16 to 18 per cent moisture willslide substantially continuously from the lower end of the screen 22 andwill fall into a sharply downwardly sloped chute 34, the lower of whichempties into a rotating barrel 36.

In one embodiment of our invention which is adapted for cleaning sandupon a comparatively small scale, that is. at the rate of approximatelytwo tons per hour, the previously described screen 22 is approximately18 inches wide and 48 inches long, while the barrel 36 is approximately5 feet long and 30 inches in diameter.

This barrel 36 is mounted to rotate about a slightly downwardly inclinedaxis upon anged rollers 38 which engage tracks 4l) secured to theexterior surface of the barrel. This barrel is driven by means of amotor 42 through a speed reducing gear box 46 and chain 4B, the chain 48engaging a sprocket 50 attached to the exterior surface of the barrel.In the embodiment shown which is adapted to have the cleaning capacitypreviously mentioned, we have found that the barrel works efhciently ina manner to be described, when rotated at a speed of from 20 to 60revolutions per minute.

Both ends of the barrel are partially enclosed by caps 52, each of whichhas an opening in the center. Thus, sand will be continuously dischargedfrom the discharge end of the barrel so long as the barrel rotates andso long as sand is fed into the inlet end of the barrel. It will beappreciated, however, that the barrel will always contain a quantity ofsand suilcient to cover the lower portion of the interior of the barrelto a, substantial depth.

Within this barrel we have placed a generally cylindrical roller |54which can be formed of a length of heavy steel pipe with a plurality oflongitudinally extending generally rectangular ribs 56 `welded to itsexternal surface. As the drum rotates, the roller 54 will rotate thereinbecause gravitational forces acting upon the roller 54 tend to maintainit in general toward the bottom portion of the barrel. In the embodimentof the invention shown, this roller is approximately 54 inches long, is9 inches in diameter, the ends are closed, and it is weighted with shotso as to have a weight of approximately 500 pounds.

As the barrel Il rotates, the sand will be tumbled therein and tend toremain in the lower portion of the barrel, while the roller 5Icontinuously rolls through the sand. The weight of the roller should lbeso adjusted that it will sink into the sand a considerable distance, butthe roller should not be so heavy that `it cuts clear through the sandand touches the inner surface of the barrel. It appears that the rollercauses the sand grains to be ground against each other underconsiderable pressure. This interaction between the sand grains whenunder pressure completely breaks loose and removes all surface depositfrom the sand grains excepting for the negligible portion of the surfacedeposit which is located in deep pits in some of the individual grainswhere it is not touched by other moving grains.

We have found that for the above beneficial inter-action to take placebetween the sand grains, several factors are of importance. In the firstplace, as has been mentioned, the roller should sink well into the sandbut should not touch the surface of the barrel. In the second place, thewater content of the sand should be suiilciently low so that the sanddoes not act` as a liquid. We have found, for instance, that a goodscrubbing or mulling action does not take place if the water content ofthe sand is greater than approximately 2G per cent. On the other hand.if the water content of the sand is lower than approximately 5 per cent,the sand grains are not efficiently cleaned. In general, it may be saidthat the water content shouldbe between the 1mits of 20 per centmoisture and 5 per cent moisture by Weight. The speed of rotation of thedrum should be suiiicient to bring about a good tumbling action andshould be fast enough so that time is not wasted by permitting the sandto remain in the barrel longer than necessary. n the other hand, thespeed of rotation must kept well below centrifuging speeds as otherwisethe water in the sand will tend to migrate toward the axis of rotation,with the result that the sand and water mixture within the drum is nolonger 'of a homogeneous consistency. As mentioned previously, for abarrel of the size given, a speed of 20 to 60 revolutions per minute issatisfactory.

In place of the single roller I, several smaller rollers may be used andif desired, these rollers, or the roller 5I can be coated with rubber.The use of rubber does not appear to affect the rate of sand cleaning toany considerable extent, but does under some conditions seem to haveless tendency to crack the grains, also, rubber coated rollers operatemore quietly and wear more slowly than steel or iron rollers.

The well mulled mixture of sand, water, carbon particles, and otherforeign substances issues from the barrel in a comparatively constantstream and falls into a hopper 58. At this point in the process themixture is black and has a gritty paste-like consistency. 'I'he above istrue if the ycore sand was oil bonded. If cement was used as a bondingagent, the mixture will be grey instead oi' black.

Water is added to the mixture in the hopper 58 through a pipe line 6Band the slurry thus formed is pumped by means of a centrifugal type pump62 or other suitable device, to a spreader flume 6I of a counterfiowclassifier, indicated generally by the numeral B8.

This sand classier comprises the before-mentioned spreader flume 6lwhich causes the incoming material to be distributed evenly over thesurface of a hopper 6B. This hopper in turn discharges at its lower endinto one or more tapered discharge tubes Til. The openings at the lowerends of these tubes in turn discharge materia-l into a hopper 12.Annular rings Il are arranged at the lower ends of the tubes 10 todirect jets of water from a pipe line Hi upwardly into these tubesandthe amount of water flowing through these jets can be regulated byvalves 1B. The water from the jets flows upwardly continuously throughthe sand in the classifier and carries with it the soluble materials.buoyant carbon particles, cement, and other refuse materials mixed withthe sand. These more buoyant particles are carried to the surface at theupper portion of the classifier and overflow into a spillway 80 whichleads to a sludge settling tank 82. The openings at the lower ends ofthe tubes lll are so proportioned that the flow of sand and watertherethrough is somewhat less than the i'low of material into theclassifier, thus a substantially constant rate of overow of water andbuoyant material into the splllway 80 is assured.

The water and sand mixture discharged from the classifier into thestorage hopper I2 is substantially free of all carbon particles andother refuse material mulled from the sand grains in the barrel 38. Thissand and water mixture is then pumped by means of a centrifugal pump B4or its equivalent to wherever it is to be dried for re-use.

Although the described apparatus includes the pipe line and the pump 32for carrying back into the tank IB the fines that pass through thescreen 22, it will be appreciated that this portion of the apparatus maybe dispensed with if the user of the process is willing to add to thereclaimed sand a small amount of fines to take the place of this lostmaterial. It will be appreciated further that the addition of thenecessary small amount of lines to take the place of this lost materialwill be relatively inexpensive, since only a small ptrtion of the finesis lost through the screen 22 inasmuch as the major portion adheres tothe larger sand particles and therefore is carried over screen 22 withthese particles. It is apparent, therefore. that whether or not thefines are to be reclaimed from the water passing down the chute 26 islargely a matter of choice to be made by the process user. In general. acomparatively large installation would probably include the necessaryapparatus to recover these lines, whereas in a small installation theslight expense of the lost fines might not justify the additional cost`of the necessary apparatus for reclaiming this srnall amount ofmaterial.

The process and apparatus described are capable of cleaning andreclaiming sand continuously rather than in batches and this feature hasan important advantage not readily preceivable on rst impression. Thisadvantage arises from the fact that a sand and water mixture is anextremely difficult material to handle efficiently, unless it containssufficient water to flow readily. I! it contains sufficient water andthe sand is in a substantially homogeneous suspension, the mixture canbe pumped, or flowed cr otherwise treated as a liquid as long as itiskept in continuous rapid motion. In a continuous process, such as abovedescribed. such continuous rapid motion is feasible. In batch processesin which the sand and water mixture must stop flowing periodically, thesand settles out of the water and fouls the system whenever the flowceases or decreases below a critical point. The result is that if a sandand water mixture handling system does not operate continuously,complicated conveyor systems are needed, since such a mixture cannot betreated as a liquid. It should be noted that in the system of thepresent invention, the sand is rapidly and continuously pumped or flowedfrom place 1o placa` as a liquid, excepting during the dewatering step,the mulling step, and the transfer step located between the dewateringand mulling steps. Such an arrangement would not be feasible exceptingin a continuous process.

The following is a typical example of the effectiveness of this processand the apparatus shown for carrying out the process. All ilgures werearrived at by performing standard tests upon standard core partsconstructed and tested in the manner recommended by the AmericanFoundrymens Association.

A typical core in a typical foundry was found to be formed of newManistee sand four parts and new Juniata sand one part. Test cores weremade in the standard manner from this new sand in which the mixtureconsisted of the following: 12,000 grams new Manistee sand, 3000 gramsJuniata sand, 232,5 grams linseed oil, and 600 c.c. water. This mixturehad a ilowability as arrived at on the standard American Foundrymen'sAssociation flowability meter of 88. Cores made from this material had apermeability when tested on the American Foundrymens Associationrecommended permeability test apparatus of 119. Five sample cores weremade of this material and baked. ano1 when tested for tensile strengthshowed the following readings on the American Foundrymen's Associationtensile testing apparatus: 43.7, 44.6, 47.7, 42.0, 45.4 or an average of44.7. Since this tensile figure is to be multiplied by live to give theactual tensile strength, the average tensile strength of these coresproved to be 223,5 pounds per square inch.

Sand was then taken from the heap of used sand in this foundry and wastreated by the before-mentioned process. This sand was then mixed fortest purposes as follows: 15,000 grams of reclaimed sand, 232.5 gramslinseed oil, and G cubic centimeters of water. That is, it was mixed inthe proportions used for the new sand. The ilowability of this mixturewas 89, or slightly better than the flowability of the mixture made fromnew sand. The permeability of the test core was 119, or exactly the sameas the core made from new sand. Five standard cores for thedetermination of tensile strength were then made and these cores gavethe following readings on the tensile test machine: 49.3, 45.7, 46.0,46.5, 48.3, or an average of 47.2. When this latter gure is multipliedby ilve. it gives the tensile strength of cores made from reclaimed sandas 236 pounds per square inch, which is materially better than the 223.5pounds per square inch obtained when new sand was used.

It is probable that sand reclaimed by the present process gives cores ofgreater strength than cores made from new sand because all new sandincludes small amounts of impurities, such as vegetable matter, whichweaken the cores made from this sand, whereas the present sand cleaningprocess removes these foreign substances. It has been found, forinstance, that new sand treated by the present process givesapproximately the same test results as used foundry sand which has beenreclaimed by this process.

From the foregoing, it will be appreciated that the present process andthe apparatus for carrying out this process are material advances in thefoundry art and that this process and the described apparatus fulfillall the objectives set forth for this invention at an earlier portion ofthis specification.

Having described our invention, what we claim as new and useful anddesire to secure by Letters Patent of the United States is:

l. Th'e method of reclaiming used foundry sand made up principally ofsaid grains coated with burned binding material which comprises mixingthe sand to be treated with water to form a ilowable mixture, passingthe flowable mixture over a screen to reduce the moisture content of themixture to between 20 per cent and 5 per cent water by weight, mullingthe resulting damp mixture so as to cause relative movement between theindividual grains, and exerting a force upon the sand during the mullingstep so as to cause the relatively moving sand grains to scrub eachother.

2. 'Ihe method of reclaiming used foundry sand made up principally ofsand grains coated with burned binding material which comprises mixingthe sand with water to form a ilowable slurry, dewatering said slurry toreduce the water content of the sand and water mixture to such a pointthat the resulting mixture is mushy in consistency, collecting the waterremoved from the mixture in the dewatering step. said water including aportion of the ne material originally mixed with the sand to be treated.reclaiming at least the heavier solid particles from the collected waterand remixing these particles with additional sand to be treated, mullingthe dewatered sand mixture so as to cause relative movement between theindividual sand grains, and exerting a force upon the sand during themulling step so as to cause the relatively moving sand grains to scrubeach other.

3. A device for reclaiming used foundry sand comprising means to store aquantity of the sand to be treated mixed with water, a dewateringscreen, means to transfer the sand and water mixture from the storagemeans to the dewatering screen at a comparatively constant rate, meansto cause the sand and a portion of the water mixed therewith to passover said screen, means to collect the material passing through saidscreen, means to transfer at least the major portion of the larger solidparticles collected by the last said means to the storage means, arotating barrel having inlet and outlet openings, means to introduce thematerial passed over said screen into the inlet opening of said barrel,a roller positioned within said barrel and adapted to rotate freelytherein, said roller being of considerably smaller diameter than theinternal diameter of the barrel, said roller being so weighted that itsinks well into the sand in said barrel, but being insufciently weightedto bring it into contact with theinner surface of said barrel, means torotate said barrel, and means to collect the material passing out of theoutlet opening of said barrel.

4. A device for reclaiming used foundry sand comprising means to store aquantity of sand to be treated mixed with water, a dewatering screen,means to transfer the sand and water mixture from the storage means tothe dewatering screen at a comparatively constant rate, means to causethe sand and a portion of the water mixed therewith to pass over saidscreen, a rotating barrel having inlet and outlet openings, means tointroduce the material passed over said screen into the inlet opening ofsaid barrel. a roller positioned within said barrel and adapted torotate freely therewith, said roller being of considerably smallerdiameter than the internal diameter of the barrel, said roller being soweighted that it sinks well into the sand in said barrel, but beinginsuiilciently Weighted to bring it into contact with the inner surfaceof said barrel, means to rotate said barrel, and means to collect thematerial passing out of the outlet opening of said barrel.

5. A device for reclaiming used foundry sand comprising means to store aquantity of sand to be treated mixed with water, a dewatering screen,means to transfer the sand and water mixture from the storage means tothe dewatering screen at a comparatively constant rate, means to causethe sand and a portion of the water mixed therewith to pass over saidscreen, a mulling device having an inlet and an outlet, means tointroduce the material passed over said screen into the inlet of saidmulling device, means in said mulling device periodically to compact thematerial therein during the mulling operation, and means to collect thematerial passed out of the outlet of said mulling device.

6. A device for reclaiming used foundry sand comprising means to store aquantity of the sand to be treated mixed with water. a dewateringscreen, means to transfer the sand and water mixture from the storagemeans to the dewatering screen at a comparatively constant rate, meansto cause the sand and a portion of the water mixed therewith to passover said screen, means to collect the material passing through saidscreen, means to transfer atleast the major portion of the larger solidparticles collected by the last said means to the storage means, amulling device having an inlet and an outlet, means to introduce thematerial passed over said screen into the inlet of said mulling device,means in said mulling device periodically to compact the materialtherein during the mulling operation, and means to collect the materialpassing out of the outlet of said mulling device.

7.- A device for reclaiming used foundry sand comprising means to mixsand to be treated with water to form a lowable mixture, dewateringmeans receiving the flowable mixture from the mixing means to remove aportion of the water therefrom and to leave the mixture mushy inconsistency, a rotating barrel having inlet and outlet openings, meansto introduce the mushy mixture from the dewatering device into the inletopening, a roller in the barrel adapted to rotate freely therein, theroller being of substantially smaller diameter than the barrel and soweighted that it sinks well into the mixture in the barrel butinsuilciently weighted to bring it into contact with the inner surfaceof the barrel, and means to rotate the barrel.

8. The method of reclaiming used foundry sand made up principally ofsand grains coated with burned binding material which comprises mixingthe sand to be treated with water to form a owable mixture, dewateringthe mixture while in a flowing stream to reduce the moisture content ofthe mixture to between 20 per cent and 5 per cent water by weight,mulling the resulting damp mixture so as to cause relative movementbetween the individual grains, and exerting a force upon the sand duringthe mulling step so as to cause the relatively moving sand grains toscrub each other.

ADRIAN DEN BREEJEN. ROY LUCE.

JASPER JAMES AMARI. DANIEL H. PETTY. RONALD Waas ne. TOWNER K. WE i TER,JR.

CERTIFICATE 0F CORRECTION.

Patent No. 2,565,0li5.

August 2l, 19145.

ADRIAN DEN BREEJEN, ET AL.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: PageZQseeond column, line 19, after "lower" insert the word end; page li,first column, line 16, for "252,5" read 252.5; line '?5,'claim l, for"said" and second column, line il, same claim, before "screen" insertand that the said letters Patent should be read with this correctiontherein that the same may conform to the record of the case in thePatent Office signed and sealed this 25th day of December, A. D. 19li5.

(Seal) Leslie Frazer First -Assistant. Commissioner oi Patents.

material passing out of the outlet opening of said barrel.

5. A device for reclaiming used foundry sand comprising means to store aquantity of sand to be treated mixed with water, a dewatering screen,means to transfer the sand and water mixture from the storage means tothe dewatering screen at a comparatively constant rate, means to causethe sand and a portion of the water mixed therewith to pass over saidscreen, a mulling device having an inlet and an outlet, means tointroduce the material passed over said screen into the inlet of saidmulling device, means in said mulling device periodically to compact thematerial therein during the mulling operation, and means to collect thematerial passed out of the outlet of said mulling device.

6. A device for reclaiming used foundry sand comprising means to store aquantity of the sand to be treated mixed with water. a dewateringscreen, means to transfer the sand and water mixture from the storagemeans to the dewatering screen at a comparatively constant rate, meansto cause the sand and a portion of the water mixed therewith to passover said screen, means to collect the material passing through saidscreen, means to transfer atleast the major portion of the larger solidparticles collected by the last said means to the storage means, amulling device having an inlet and an outlet, means to introduce thematerial passed over said screen into the inlet of said mulling device,means in said mulling device periodically to compact the materialtherein during the mulling operation, and means to collect the materialpassing out of the outlet of said mulling device.

7.- A device for reclaiming used foundry sand comprising means to mixsand to be treated with water to form a lowable mixture, dewateringmeans receiving the flowable mixture from the mixing means to remove aportion of the water therefrom and to leave the mixture mushy inconsistency, a rotating barrel having inlet and outlet openings, meansto introduce the mushy mixture from the dewatering device into the inletopening, a roller in the barrel adapted to rotate freely therein, theroller being of substantially smaller diameter than the barrel and soweighted that it sinks well into the mixture in the barrel butinsuilciently weighted to bring it into contact with the inner surfaceof the barrel, and means to rotate the barrel.

8. The method of reclaiming used foundry sand made up principally ofsand grains coated with burned binding material which comprises mixingthe sand to be treated with water to form a owable mixture, dewateringthe mixture while in a flowing stream to reduce the moisture content ofthe mixture to between 20 per cent and 5 per cent water by weight,mulling the resulting damp mixture so as to cause relative movementbetween the individual grains, and exerting a force upon the sand duringthe mulling step so as to cause the relatively moving sand grains toscrub each other.

ADRIAN DEN BREEJEN. ROY LUCE.

JASPER JAMES AMARI. DANIEL H. PETTY. RONALD Waas ne. TOWNER K. WE i TER,JR.

CERTIFICATE 0F CORRECTION.

Patent No. 2,565,0li5.

August 2l, 19145.

ADRIAN DEN BREEJEN, ET AL.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: PageZQseeond column, line 19, after "lower" insert the word end; page li,first column, line 16, for "252,5" read 252.5; line '?5,'claim l, for"said" and second column, line il, same claim, before "screen" insertand that the said letters Patent should be read with this correctiontherein that the same may conform to the record of the case in thePatent Office signed and sealed this 25th day of December, A. D. 19li5.

(Seal) Leslie Frazer First -Assistant. Commissioner oi Patents.

